Variable volume devices utilized as pneumatic or fluid motors, compressors, internal or external combustion engines, and the like are known in many variations and configurations. In positive displacement devices, for example, the use of a reciprocating piston fitted into a cylinder and sealed by means of rings extending circumferentially around the piston is well known.
Other arrangements having apparent advantages, due, at least in part, to the mechanical configurations utilized, have also heretofore been suggested and/or utilized, such as the Wankel rotary engine, for example. Such arrangements have not, however, proved to be complete successful, and have been found to have drawbacks in the sealing utilized between the static and moving components.
In addition, a relatively old design by Root has also been proposed, and this design suggests the use of inner and outer rectangular pistons moving in transverse directions to vary the volumes of a plurality of rectangular chambers. Examples of such a structure can be found, for example, in U S. Pat. No. 2,013,862 and British Patent No. 479,705.
The advantages of light weight relative to displacement, compactness, simplicity of parts, etc. of a device based upon Root's design are readily apparent. However, despite these apparent advantages, no widely accepted utilization of such a design has resulted, and it is felt that this lack of practical application is attributable, at least in part, to the difficulty of effectively sealing the chambers of such devices. In this respect, it should be noted that with a reciprocating cylindrical piston the greatest forces are transverse to the direction of sealing, while with a rectangular piston arrangement substantial force is encountered at the sealing area between the inner and outer pistons and this complicates the task of providing effective and efficient sealing therebetween.
Sealing apparatus providing a useful sealing arrangement for piston structures reciprocated in directions transverse to one another is shown and claimed in copending U.S. patent application Ser. No. 332,502, filed Nov. 18, 1981, and issued Aug. 21, 1984 as U.S. Pat. No. 4,466,335, by the inventor of this invention. In addition, nutation valving apparatus is shown and claimed in U.S. patent application Ser. No. 474,829, now issue 1/13/86, filed Mar. 14, 1983, by the inventor of this invention.